The present invention relates to signal attenuators and in particular to a multi-stage variable signal attenuator.
Loran receivers determine the position of ships at sea or aircraft by comparing the timing of signals generated by two synchronized transmitters spaced some distance apart. To test and calibrate a Loran receiver, it is useful to simulate the transmissions of the two transmitters by applying two such signals to the receiver, varying the relative timing of the signals and checking the resulting position data produced by the receiver. In simulating the transmissions of the two transmitters, it would be useful to vary the signal strength of either signal to simulate the differences in distance to the transmitters from the receiver. However attenuators typically comprise transmission lines which delay or distort a signal by at least a small amount and the delay or distortion of one signal by even a small amount can cause a large error in the apparent position data generated by a Loran receiver.